How do you know if your spouse is cheating?

[Diamond]

I've always felt like if my husband was cheating, I would just "know" or some how find out. I always thought snooping to find out was unnecessary. But, lately I've been wondering and when I sit back and think about things I realize some things that make me wonder if he is or has cheated.

One thing that really got me thinking was a couple of nights ago we somehow got in an argument about what was really considered "cheating" (can't remember how the conversation started) but he spent about an hour trying to convince me that having sex with someone else is not cheating. According to him it's only cheating if you have a "full blown 'relationship'". That got me wondering....'why is he trying to prove this?' Then I think about what time he gets off work, versus what time he actually comes home. I'm usually so tied up with our 3 year old that I don't really pay attention, but there can be a good 2 hours of a time gap.

Then on top of that he only works part time but often claims that he doesn't have time to look for more work. I work full time and have worked full time for at least the last 5 years and working full time has never stopped me from having time to look for a new job if I wanted/needed one. So that makes me wonder.... what is he doing with all this extra time??

He also keeps his phone locked with a password at all times and won't tell me what it is, so even if I need to use his phone I have to get him to unlock it and he claims he does that because I'm 'secretive and don't let him see my stuff', but I text all the time and he can go in any time he wants and look cause there's nothing but girl talk in mine. Then, he deleted me from his Facebook and says he did it because I added a guy that I dated back when I was a teenager, before we were married and says he hates the guy if I'm going to have him on my Facebook he doesn't want me on his.

I'm very suspicious of him trying to convince me that just having sex with someone with a "relationship" is not cheating because that really makes me think he has done that and feels it's ok. But how would I ever know for sure, other than catching him in the act???? I don't even see him on the phone or texting much where I would think he's talking to someone else.